This invention relates to a valve gear assembly for an internal-combustion engine comprising at least two inlet strike valves per cylinder which act in parallel, are each actuated by a cam as well as a transfer element and the courses of the valve strokes of the stroke valves are adjustable so that they differ from one another.
A valve gear assembly of this type is known, for example, from German Patent Document 37 39 246 A1. In this case, the transfer element is constructed as a valve lifter, and individual valve lifters of the stroke valves assigned to a single cylinder can be connected with one another by way of coupling elements. By assigning in this state of the art different cams to the individual valve lifters, it is possible to actuate, by means of the corresponding control of these valve lifter couplings, a defined stroke valve either directly by the cam assigned to it or by the cam of another stroke valve. The course of the valve stroke of this defined stroke valve can therefore be changed in a different manner than that of another stroke valve.
This known valve gear assembly is disadvantageous in that only stroke courses can be generated on the individual stroke valves which are predetermined by the actually existing cams. Further variations are not possible in this case. Also the coupling elements of the valve lifters or transfer elements experience extremely high mechanical stress.
It is therefore an object of the invention to indicate measures carried out on a valve gear assembly comprising an least two stroke valves per cylinder which act in parallel to one another, by means of which measures the courses of the stroke valves can be adjusted in a varied manner and differently from one another.
For achieving this object, it is provided that the supporting points of the transfer elements can be adjusted by way of rotatable eccentrics disposed on a common eccentric shaft, the elevation curves of the at least two eccentrics per cylinder differing from one another. Advantageous further developments are contained in preferred embodiments of the invention.
According to the invention, the supporting points of the transfer elements which are connected between the individual cams as well as the individual valves can be adjusted. These transfer elements may be a valve lifter as in the above-mentioned state of the art or a valve lever or rocker lever; however, other embodiments are also conceivable, such as a link or crank element having a link path for a roller. When the supporting point of this rocker lever or valve lifter or link element is displaced, a changed course of the stroke will occur for the respective assigned stroke valve because the cam stroke is transferred in a different manner. Although this principle of varying the course of the valve stroke is known per se (German Patent Document DE 38 33 540 C2), this known construction does not indicate how the supporting point of the transfer element can be displaced in a simple manner.
According to the invention, this takes place by means of eccentrics on which the transfer elements are supported. These eccentrics are part of a common eccentric shaft--if several cylinders are arranged in a row, this eccentric shaft may extend along all cylinders--which can be rotated in a simple manner. Furthermore, according to the invention, the eccentrics differ which are assigned to a single cylinder. It is therefore possible to actuate the valves assigned in turn, as desired, to these individual eccentrics in manners that differ from one another, or to adjust the courses of their stroke in manners that differ from one another.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.